The present invention relates to a process for producing 3-1-menthoxypropane-1,2-diol useful as a cooling agent and a refrigerant, and to a 3-1-menthoxypropane derivative useful as an intermediate for producing 3-1-menthoxypropane-1,2-diol and a process for producing the same. According to the invention, highly pure 3-1-menthoxypropane-1,2-diol and 3-1-menthoxypropane derivatives useful as synthetic intermediates for 3-1-menthoxypropane-1,2-diol can be obtained safely and in high yields through simple operations.
3-1-Menthoxypropane-1,2-diol is a known compound as described in Japanese Patent Publication No. 48813/1986. 3-1-Menthoxypropane-1,2-diol is excellent in safety and also have a nature of imparting a cooling effect on skin and mucous membrane like 1-menthol. On the other hand, it is odorless unlike 1-menthol, and itself has no smell. Therefore, in the case of using 3-1-menthoxypropane-1,2-diol, a cooling effect can be imparted to a product without affecting the fragrance imparted to the product. Thus, utilizing the above characteristic of 3-1-menthoxypropane-1,2-diol, 3-1-menthoxypropane-1,2-diol has been blended with oral compositions such as tooth paste and chewing gum, and food and drink such as sherbet and hard candies, and further, it has been proposed to blend it with toilet articles such as cosmetics (Published Japanese Patent Application Nos. 25908/1985 and 208505/1988), an eye-pack agent (Published Japanese Patent Application No. 96403/1987) and a hair cosmetic (Published Japanese Patent Application No. 192312/1987), and others such as an aerosol composition for anti-inflammatory agents (Published Japanese Patent Application No. 264522/1988).
Processes for producing 3-1-menthoxypropane-1,2-diol which are known heretofore include (i) a process wherein 1-menthol is converted to the sodium salt with metal sodium or sodium hydride, then an allyl halide is reacted therewith to produce 3-1-menthoxypropan-1-ene, and it is oxidized using an organic peroxide to form an oxide, followed by hydrolysis (Japanese Patent Publication No. 48813/1986), and (ii) a process wherein 1-menthol is added to benzyl glycidyl ether in the presence of a Lewis acid to produce 1-benzyloxy-3-1-menthoxypropan-2-ol and it is subjected to hydrogenolysis in the presence of palladium-carbon catalyst to eliminate the benzyl group (Published Japanese Patent Application No. 82200/1995).
However, in the above conventional method (i), sodium salt of 1-menthol is produced with metal sodium or sodium hydride, and therefore there are problems of the risk of explosion and the generation of hydrogen gas. Furthermore, an intermediate of 3-1-menthoxypropan-1-ene is oxidized with an organic peroxide, and thus the risk of explosion also exists at the use. Accordingly, the process is not regarded as an industrially advantageous one and also some improvement is required from an economical point of view.
Moreover, since the above conventional process (ii) is a process for the purpose of synthesizing an optical isomer, it is necessary to use expensive benzyl glycidyl ether. In addition, 3-1-menthoxypropane-1,2-diol finally obtained contains about 10% of 2-1-menthoxypropane-1,3-diol as a by-product, so that the purification or fractionation by silica gel column chromatography or the like is necessary and thus it is difficult to obtain a large amount of highly pure 3-1-menthoxypropane-1,2-diol.
Furthermore, other than the above conventional processes, proposed is (iii) a process wherein 1-menthol is added to a 1,2-epoxy-3-halogenopropane such as epichlorohydrin in an aqueous solution in the presence of a base and a quaternary ammonium salt to produce 1,2-epoxy-3-1-menthoxypropane which is a synthetic intermediate for 3-1-menthoxypropane-1,2-diol [French Patent No. 2479822 (1981)]. However, 1,2-epoxy-3-halogenopropane such as epichlorohydrin is known to be unstable and prone to decompose in the presence of an acid or a base [xe2x80x9cKagaku Daijitenxe2x80x9d, p. 292, published by Tokyo Kagaku Dojin (1989)]. Therefore, in the case of this process where a 1,2-epoxy-3-halogenopropane is reacted in the presence of a base, the 1,2-epoxy-3-halogenopropane decomposes when the reaction takes a long period of time, so that it is difficult to synthesize 1,2-epoxy-3-1-menthoxypropane, and thus this process is not regarded as an advantageous process from industrial and economical viewpoints.
Furthermore, as the reaction between epichlorohydrin and an alcohol, proposed is (iv) a process for producing 1-allyloxy-3-chloro-2-propanol by reacting epichlorohydrin with allyl alcohol in the presence of an acidic catalyst (Published Japanese Patent Application No. 221/1990). In this conventional process (iv), however, the alcohol to be used in the reaction is only primary allyl alcohol and the application to a secondary alcohol, much less the addition reaction with menthol, is not reported.
In addition, as another conventional process, there is proposed (v) a process wherein an epihalohydrin is reacted with an alcohol in the presence of an acid catalyst, then the product is treated with an alkali to form a glycidyl ether through ring closure, and after hydrolysis, the reaction mixture is heated at 100 to 230xc2x0 C. in the presence of a salt formed from a strongly basic compound and a weakly acidic compound to produce a glycerol ether (Published Japanese Patent Application No. 212114/2000). However, in order to decompose an organohalogen contained in hydrolyzate of the glycidyl ether, this process requires heating the reaction mixture at a high temperature of 100 to 230xc2x0 C., especially 150 to 200xc2x0 C. in the presence of a salt formed from a strongly basic compound and a weakly acidic compound, and thus is not an efficient process. Furthermore, the alcohol to be used in the process is a primary alcohol represented by the general formula: Rxe2x80x94(OA)pxe2x80x94OH (wherein R represents a saturated or unsaturated linear or branched hydrocarbon group having 1 to 36 carbon atoms, A represents an alkylene group having 2 to 4 carbon atoms, and p represents one number of 0 to 100), and the use of secondary alcohol is not disclosed, much less the use of menthol is not disclosed at all.
An object of the invention is to provide a process for producing highly pure 3-1-menthoxypropane-1,2-diol safely and in high yields through simple operations.
Other object of the invention is to provide an intermediate useful for obtaining highly pure 3-1-menthoxypropane-1,2-diol.
Still other object of the invention is to provide a process for producing intermediates useful for obtaining 3-1-menthoxypropane-1,2-diol efficiently.
The present inventors have extensively studied for achieving the above objects. As a result, a novel compound of a 1-halogeno-3-1-menthoxypropan-2-ol can be produced by adding 1-menthol to a 1,2-epoxy-3-halogenopropane in an organic solvent in the presence of a Lewis acid. And, as a result of further studies, they have found that the novel 1-halogeno-3-1-menthoxypropan-2-ol is chemically stable and can be stored by itself, and 1,2-epoxy-3-1-menthoxypropane, which is also an intermediate for obtaining 3-1-menthoxypropane-1,2-diol, is obtained at a high reaction rate and in high yields by further epoxidating the 1-halogeno-3-1-menthoxypropan-2-ol with a base in the presence of a phase transfer catalyst, and objective 3-1-menthoxypropane-1,2-diol is obtained conveniently in good yields and at a high purity by hydrolyzing the 1,2-epoxy-3-1-menthoxypropane. Based on these findings, they have accomplished the invention.
Namely, the invention relates to:
(1) a process for producing 3-1-menthoxypropane-1,2-diol, which comprises:
adding 1-menthol to a 1,2-epoxy-3-halogenopropane represented by the following general formula (I): 
(wherein X represents a halogen atom),
in an organic solvent in the presence of a Lewis acid to produce a 1-halogeno-3-1-menthoxypropan-2-ol represented by the following general formula (II): 
(wherein X represents a halogen atom),
then, epoxidating it with a base in the presence of a phase transfer catalyst to produce a 1,2-epoxy-3-1-menthoxypropane represented by the following chemical formula (III): 
and further hydrolyzing it to produce 3-1-menthoxypropane-1,2-diol represented by the following chemical formula (IV). 
And, the invention relates to:
(2) a process for producing 3-1-menthoxypropane-1,2-diol, which comprises:
epoxidating a 1-halogeno-3-1-menthoxypropan-2-ol represented by the following general formula (II): 
(wherein X represents a halogen atom),
with a base in the presence of a phase transfer catalyst to produce a 1,2-epoxy-3-1-menthoxypropane represented by the following chemical formula (III): 
and further hydrolyzing it to produce 3-1-menthoxypropane-1,2-diol represented by the following chemical formula (IV). 
Further, the invention relates to:
(3) a process for producing a 1-halogeno-3-1-menthoxypropan-2-ol, which comprises:
adding 1-menthol to a 1,2-epoxy-3-halogenopropane represented by the following general formula (I): 
(wherein X represents a halogen atom),
in an organic solvent in the presence of a Lewis acid to produce a 1-halogeno-3-1-menthoxypropan-2-ol represented by the following general formula (II): 
(wherein X represents a halogen atom).
And, the invention relates to:
(4) a process for producing a 1,2-epoxy-3-1-menthoxypropane, which comprises:
epoxidating a 1-halogeno-3-1-menthoxypropan-2-ol represented by the following general formula (II): 
(wherein X represents a halogen atom),
with a base in the presence of a phase transfer catalyst to produce a 1,2-epoxy-3-1-menthoxypropane represented by the following chemical formula (III). 
And, the invention includes:
(5) the process as in any one of the above (1) to (4), wherein X is chlorine atom in the 1,2-epoxy-3-halogenopropane represented by the above general formula (I) and the 1-halogeno-3-1-menthoxypropan-2-ol represented by the above general formula (II);
(6) the process as in the above (1) or (3), wherein the Lewis acid is at least one selected from boron trifluoride ether complex, aluminum chloride, zinc chloride, zinc bromide and ferric chloride; and
(7) the process as in the above (1), (2), (4), (5) or (6), wherein the phase transfer catalyst is a quaternary ammonium salt;
as preferred embodiments.
Furthermore, the invention relates to:
(8) a 1-halogeno-3-1-menthoxypropan-2-ol represented by the following general formula (II): 
(wherein X represents a halogen atom).
And, the invention includes:
(9) 1-chloro-3-1-menthoxypropan-2-ol represented by the following chemical formula (IIa). 
as a preferred embodiment.
The following will explain the invention in detail.
The process of the invention for producing 3-1-menthoxypropane-1,2-diol is carried out according to the following reactions. 
(wherein X represents a halogen atom)
Namely, 1-menthol is added to a 1,2-epoxy-3-halogenopropane (I) in an organic solvent in the presence of a Lewis acid to produce a novel 1-halogeno-3-1-menthoxypropan-2-ol (II). Then, the 1-halogeno-3-1-menthoxypropan-2-ol (II) is epoxidated with a base in the presence of a phase transfer catalyst to produce 1,2-epoxy-3-1-menthoxypropane (III), and 3-1-menthoxypropane-1,2-diol (IV) is obtained by hydrolyzing it.
As a halogen atom X in the 1,2-epoxy-3-halogenopropane (I), fluorine atom, chlorine atom, bromine atom, iodine atom, and the like may be mentioned. Thus, specific examples of the 1,2-epoxy-3-halogenopropane include 1,2-epoxy-3-fluoropropane (epifluorohydrin), 1,2-epoxy-3-chloropropane (epichlorohydrin), 1,2-epoxy-3-bromopropane (epibromohydrin), 1,2-epoxy-3-iodopropane (epiiodohydrin), and the like. Among them, preferably used in the invention is 1,2-epoxy-3-chloropropane (epichlorohydrin) or 1,2-epoxy-3-bromopropane (epibromohydrin), the halogen atom X being chlorine atom or bromine atom, and more preferably used is 1,2-epoxy-3-chloropropane (epichlorohydrin).
Commercially available 1,2-epoxy-3-halogenopropane (I) and 1-menthol as they are can be used as starting materials.
The addition of 1-menthol to a 1,2-epoxy-3-halogenopropane (I) is necessarily carried out in an organic solvent in the presence of a Lewis acid. When a brxc3x8nsted acid (protonic acid), a Grignard reagent or a base is used instead of a Lewis acid, an adduct (1-halogeno-3-1-menthoxypropane or 1,2-epoxy-3-1-menthoxypropane) is not formed or is formed only in low yields.
At the addition of 1-menthol to a 1,2-epoxy-3-halogenopropane (I), preferably adopted is the method wherein a Lewis acid is added to a solution of 1-menthol dissolved in an organic solvent, and then, a solution of 1,2-epoxy-3-halogenopropane (I) dissolved in an organic solvent is added dropwise thereto to carry out the reaction.
The molecular ratio of the 1,2-epoxy-3-halogenopropane (I) and 1-menthol to be used is preferably from about 0.8 to 2 mol, more preferably from 0.9 to 1.3 mol of 1-menthol relative to 1 mol of the 1,2-epoxy-3-halogenopropane (I).
Moreover, the amount of the Lewis acid to be used may be a similar amount to the amount of a catalyst in a conventional addition reaction, and is, in general, preferably from about 0.01 to 0.1 mol relative to 1 mol of the 1,2-epoxy-3-halogenopropane (I).
Specific examples of the Lewis acid include boron trifluoride ether complex, aluminum chloride, zinc chloride, zinc bromide, ferric chloride, and the like. One or two or more of them may be used. Among them, aluminum chloride and/or boron trifluoride ether complex are preferably used in view of good operability and economically low cost.
As the organic solvent, use is made of an organic solvent which does not affect adversely the addition of 1-menthol to a 1,2-epoxy-3-halogenopropane (I). Specific examples thereof include aliphatic hydrocarbon solvents such as hexane, heptane and octane; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; petroleum ether solvents, and the like. One or two or more of them may be used. Among them, heptane and/or toluene are preferably used in view of good operability and economically low cost.
In general, the ratio of the organic solvent to be used to 1-menthol (volume/weight) is preferably from about 0.5 to 5, more preferably about 1 to 3.
The addition of 1-menthol to a 1,2-epoxy-3-halogenopropane (I) is preferably carried out under an atmosphere of an inert gas such as nitrogen gas or argon gas for smooth proceeding of the addition reaction.
Moreover, at carrying out the addition reaction by adding dropwise a solution of a 1,2-epoxy-3-halogenopropane (I) dissolved in an organic solvent to a solution of 1-menthol and a Lewis acid dissolved in an organic solvent, the time for adding the solution of the 1,2-epoxy-3-halogenopropane (I) dissolved in an organic solvent is, in general, preferably about 0.5 to 10 hours, more preferably about 1.5 to 3 hours.
The temperature for the addition reaction is preferably about 60 to 130xc2x0 C., more preferably about 65 to 120xc2x0 C. A 1-halogeno-3-1-menthoxypropan-2-ol (II) can be smoothly produced by the reaction for about 0.5 to 15 hours, preferably about 1 to 5 hours after completion of the addition of the organic solvent solution of a 1,2-epoxy-3-halogenopropane (I) with maintaining the above temperature.
The 1-halogeno-3-1-menthoxypropan-2-ol (II) obtained by the above addition reaction is a novel compound hitherto unknown, and is stable, usually oily, and storable.
Therefore, the 1-halogeno-3-1-menthoxypropan-2-ol (II) obtained by the above addition reaction may be stored after purification by, for example, distillation or column chromatography or without any purification, and at the production of 1,2-epoxy-3-1-menthoxypropane or 3-1-menthoxypropane-1,2-diol (IV), the compound (II) may be taken out of a storing vessel and used. Alternatively, the 1-halogeno-3-1-menthoxypropan-2-ol (II) formed by the above addition reaction may be directly used for the next epoxidation reaction without additional-treatment such as purification, after cooling according to need.
The 1-halogeno-3-1-menthoxypropan-2-ol (II) obtained by the above addition reaction is epoxydated with a base in the presence of a phase transfer catalyst to produce 1,2-epoxy-3-1-menthoxypropane (III).
As the base to be used in the epoxidation reaction, hydroxide, carbonate and/or an alkoxide of an alkali metal or alkaline earth metal may be used. Specific examples thereof include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, and the like. One or two or more of them may be used. Among them, sodium hydroxide and/or potassium hydroxide are preferably used.
The base is preferably added to the reaction system in the form of an aqueous solution. The concentration of the aqueous solution of the base is preferably 40% or more, especially a high concentration of 45 to 55% because of the smooth proceeding of the epoxidation reaction.
The amount of the base to be used is preferably from about 1.0 to 5.0 mol, particularly about 1.5 to 3.0 mol relative to 1 mol of the 1-halogeno-3-1-menthoxypropan-2-ol (II).
As the phase transfer catalyst to be used in the above epoxidation reaction, a quaternary ammonium salt is suitably used, and specific examples thereof include industrially easily available quaternary ammonium salts such as tetramethylammonium chloride, tetrabutylammonium bromide, tetraethylammonium iodide, tetrabutylammonium iodide, trimethylhexadecylammonium chloride, dimethyldioctylammonium chloride, trimethylbenzylammonium chloride and trioctylmethylammonium chloride. One or two or more of them may be used. Among them, trimethylbenzylammonium chloride is preferably used in view of smooth proceeding of the epoxidation reaction and economically low cost.
The amount of the phase transfer catalyst to be used is preferably from about 0.01 to 0.2 mol, particularly about 0.02 to 0.05 mol relative to 1 mol of the 1-halogeno-3-1-menthoxypropan-2-ol (II).
The above epoxidation reaction is preferably carried out in an organic solvent. As the organic solvent, there may be mentioned organic solvents which do not affect adversely the epoxidation reaction, for example, aliphatic hydrocarbon solvents such as hexane, heptane and octane; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; ether solvents such as diethyl ether, diisopropyl ether, dimethoxyethane, tetrahydrofuran, dioxane and 1,3-dioxolane; petroleum ether solvents, and the like. One or two or more of them may be used. Among them, toluene and/or heptane are preferably used in view of smooth proceeding of the epoxidation reaction as well as good operability and economically low cost.
The amount of the organic solvent to be used is preferably from about 1 to 10 parts by volume, particularly about 2 to 5 parts by volume relative to 1 part by volume of the 1-halogeno-3-1-menthoxypropan-2-ol (II).
The above epoxidation reaction is preferably carried out under an atmosphere of an inert gas such as nitrogen gas or argon gas.
The temperature for the epoxidation reaction is preferably about 40 to 100xc2x0 C., particularly about 50 to 80xc2x0 C. 1,2-Epoxy-3-1-menthoxypropane (III) can be smoothly produced by the reaction for about 0.5 to 6 hours, preferably about 1 to 4 hours with maintaining the above temperature.
The 1,2-epoxy-3-1-menthoxypropane (III) obtained by the above epoxidation reaction is oily and storable. Therefore, the 1,2-epoxy-3-1-menthoxypropane (III) obtained by the above epoxidation reaction may be stored after purification by, for example, distillation or column chromatography or without any purification, and at the production of 3-1-menthoxypropane-1,2-diol (IV), the former compound may be taken out of a storing vessel and used. Alternatively, the 1,2-epoxy-3-1-menthoxypropane (III) obtained by the above epoxidation reaction may be directly used for the production of 3-1-menthoxypropane-1,2-diol (IV) without additional-treatment such as purification, after cooling according to need.
3-1-Menthoxypropane-1,2-diol (IV) is formed by hydrolyzing 1,2-epoxy-3-1-menthoxypropane (III) obtained by the above epoxidation reaction.
The hydrolysis of 1,2-epoxy-3-1-menthoxypropane (III) is preferably carried out in the presence of an acidic catalyst. Examples of the acidic catalyst include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, perchloric acid and phosphoric acid; organic acids such as acetic acid, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and camphorsulfonic acid; and the like. Among them, sulfuric acid and/or perchloric acid are preferably used in view of smooth proceeding of the hydrolysis and economically low cost.
The amount of the acidic catalyst to be used is preferably from about 0.02 to 0.2 equivalent, particularly about 0.05 to 0.15 equivalent relative to 1 mol of the 1,2-epoxy-3-1-menthoxypropane (III).
The acidic catalyst is preferably added to the reaction system in the form of an aqueous solution. The concentration of the aqueous solution of the acidic catalyst is preferably about 1 to 15%.
The above hydrolysis is preferably carried out in an organic solvent. Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, diisopropyl ketone, methyl tert-butyl ketone and cyclohexanone; ether solvents such as diisopropyl ether, dimethoxyethane, tetrahydrofuran, dioxane and 1,3-dioxolane; and the like. One or two or more of them may be used. Among them, acetone is preferably used in view of economically low cost.
The amount of the organic solvent to be used is preferably from about 1 to 10 parts by volume, particularly about 2 to 5 parts by volume relative to 1 part by volume of 1,2-epoxy-3-1-menthoxypropane (III).
The temperature for the above hydrolysis is preferably about 20 to 100xc2x0 C., more preferably about 50 to 80xc2x0 C. 3-1-Menthoxypropane-1,2-diol (IV) can be produced by the reaction for about 0.5 to 5 hours, preferably about 1 to 3 hours with maintaining the above temperature. Isolation of 3-1-menthoxypropane-1,2-diol (IV) from the reaction product containing 3-1-menthoxypropane-1,2-diol (IV) can be carried out according to a conventional method. Although the method of recovery is not particularly limited, 3-1-menthoxypropane-1,2-diol (IV) can be isolated as a concentrate, for example, in the case that a water-soluble organic solvent is used in the reaction, by adding water to the reaction mixture according to need, removing the water-soluble organic solvent used in the reaction by evaporation, adding thereto an alkaline aqueous solution and a hydrocarbon organic solvent such as hexane, butane, benzene, toluene or xylene to neutralize the acidic catalyst used and to extract 3-1-menthoxypropane-1,2-diol (IV) with an organic solvent, and finally removing the solvent by evaporation. Purification of 3-1-menthoxypropane-1,2-diol (IV) can be effected by distillation or column chromatography.
3-1-Menthoxypropane-1,2-diol (IV) obtained as above is used for a variety of applications such as cosmetics, toiletry goods, bath agents, food and drink, medicines, and the like with making good use of the characteristics such as cooling effect, refreshing effect, odorless property and safety. Examples thereof include various lotions such as body lotion, after-shave lotion and hair-growth lotion; skin cosmetics such as washing cream, vanishing cream, cleansing cream, cold cream, emulsion, toilet water, facial mask, makeup remover and lip cream; cataplasm, plaster, nasal decongestant, antiperspirant; hair-care goods such as shampoo, rinse, treatment and conditioner; hair cosmetics such as hair tonic, hair cream and hair spray; perfumes, colognes; bath agent, body shampoo, soap; shaving foam and gel; detergents, softeners; in-door aromatic agent; tooth paste; mouth wash; ointment; food and drink such as refreshing drink, gum, candy, ice cream, sherbet, jelly, tablet, troche; and the like.
The following will explain the invention concretely with reference to Examples, but the invention is not limited at all by following Examples.
By the way, in following Examples, the instruments used for measuring or analyzing physical properties are as follows.
(1) Chemical purity
Gas chromatograph: xe2x80x9cHP6890xe2x80x9d manufactured by HEWLETT PACKARD
Column: xe2x80x9cNEUTRABOND-1xe2x80x9d manufactured by G L Science (inner diameterxc3x97length=0.25 mmxc3x9730 m)
(2) Nuclear magnetic resonance spectrum:
1H-NMR: xe2x80x9cDRX-500 typexe2x80x9d (500 MHz) manufactured by Bruker
(3) Infrared absorption spectrum:
Instrument: xe2x80x9cNicolet AVATAR 360xe2x80x9d manufactured by Nicolet Japan K.K.
Measuring method: NaCl film method
(4) Mass spectrum (MS):
M-80 mass spectrometer: manufactured by Hitachi Ltd. (ionization voltage, 20 eV)
(5) Polarimeter:
DIP-360 manufactured by Nihon Bunko K.K.